Wind energy has been most prevalently utilized to generate electric power due to non pollution to the environment and the conservation of fossil fuel resources. The energy generated from wind turbine depends on the wind site characteristics and the wind turbine parameters. So, the choice of certain wind turbine for specific site is very important in terms of price of electric energy generated from wind energy system. Therefore, optimal choice of wind turbine is one of the most crucial issues in the design of wind energy system, which can utilize wind energy as efficiently as possible and achieve the best economic benefits. So this paper introduces a new and simple mathematic formulation for the wind turbine-site matching problem, based on wind speed characteristics of any site and the power curve parameters of any wind turbine. Wind speed at any site is characterized by the scale parameter (c) and the shape parameter (k) of the Weibull distribution function. The power curve parameters of any wind turbine are characterized by the cut-in, rated, and furling speeds and the rated power. The new formulation method is derived based on a generic formulation for the product of the Capacity Factor (CF) and Normalized Power (PN). Three case studies are also presented to demonstrate the effectiveness of the proposed method to choose between a group of wind sites and a list of commercial wind turbines.